Preparation method of multi-size white bamboo wood capable of being patterned

Abstract

The invention provides a preparation method of multi-size patterned white bamboos, which comprises the following steps: selecting mature bamboos with intact appearance, cutting the bamboos into required sizes, and polishing off a wax coat on the surface and a thin film in the bamboos; then carrying out drying treatment at the temperature of 80 to 110 DEG C, wherein the drying time is 24 to 72 hours; putting the bamboo wood into an alkaline solution, soaking for 10-20 minutes at normal temperature, taking out and airing, and coating the surface of the bamboo wood with a bleaching solution; the bamboo wood is placed under a light source for illumination, and photocatalytic oxidation is conducted till the whole color or the local color of the bamboo wood becomes white; and then the bamboo wood is placed in an organic solvent, after ultrasonic cleaning is conducted for 5-10 min, natural drying is conducted, and the white bamboo wood is obtained. The preparation method of the multi-size patterned white bamboo wood is simple in process and not limited by the size of raw materials, the overall white bamboo wood can be prepared, the local patterned white bamboo wood can also be prepared, the structural integrity of the bamboo wood can be kept while high whiteness (larger than or equal to 90%) is achieved, and the prepared white bamboo wood is high in mechanical strength.

Description

Technical Field

[0001] The invention belongs to the technical field of bamboo materials, and in particular relates to a method for preparing multi-sized and patternable white bamboo materials. Background Art

[0002] my country is rich in bamboo resources and is known as the "Bamboo Kingdom". Compared with wood, bamboo has the advantages of short maturity period, good mechanical properties, mildew resistance and antibacterial properties. "Replacing wood with bamboo" and "beating wood with bamboo" are the main goals of bamboo processing and utilization in my country. my country's bamboo wood-based panel industry has grown in scale, and a variety of products including bamboo floors, bamboo wall panels, bamboo furniture and bamboo decorative materials have been marketed, creating a lot of social and economic benefits. Bamboo is an anisotropic natural polymer material, mainly composed of cellulose, hemicellulose and lignin. The lignin in bamboo makes bamboo appear brownish yellow, and the internal components are not completely consistent, resulting in differences in bamboo color. In addition, the presence of lignin makes bamboo easy to change color during use, and at the same time limits the application of bamboo in the field of light management.

[0003] The methods for preparing white bamboo by decolorizing bamboo in the prior art mainly include: removing lignin, in-situ lignin modification and other two strategies. Patents CN110978183A and CN113386223A use a mixed solution of sodium chlorite / glacial acetic acid to remove lignin from bamboo to prepare white bamboo; Patent CN106243391A uses hydrogen peroxide and ammonia water to remove all wood lignin. These methods completely remove the lignin that plays a bonding role in bamboo, and the method of soaking bamboo in the solution for a long time easily breaks the hydrogen bond connection of bamboo cellulose, causing the bamboo to easily absorb water and swell, making the structure of the bamboo after bleaching very loose, very easy to crack and break, and poor mechanical properties. Therefore, it is urgent to develop a preparation method that can achieve efficient bleaching of bamboo and ensure that the bamboo maintains structural stability and high mechanical properties after bleaching. Summary of the invention

[0004] In view of this, in order to solve the above technical problems, the present invention proposes a method for preparing multi-size, patternable white bamboo materials, which has a simple process, is not limited by the size of raw materials, can prepare both whole white bamboo materials and partially patterned white bamboo materials, and can maintain the structural integrity of the bamboo materials while achieving a higher whiteness (≥90%), and the prepared white bamboo materials have high mechanical strength.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A method for preparing multi-size, patternable white bamboo material comprises the following steps:

[0007] S1. Selection and pretreatment of bamboo: Select mature bamboo with good appearance, cut it into required size, and polish off the wax layer on the surface and the film inside;

[0008] S2, drying of bamboo materials: drying the bamboo materials obtained in S1 at 80-110° C. for 24-72 hours;

[0009] S3, bleaching liquid treatment: placing the bamboo obtained in S2 in an alkaline solution, soaking for 10 to 20 minutes at room temperature, taking it out to dry, and then applying bleaching liquid on the surface of the bamboo;

[0010] S4, light treatment: placing the bamboo obtained in S3 under a light source for photocatalytic oxidation until the overall color or partial color of the bamboo turns white;

[0011] S5, cleaning: placing the bamboo material obtained in S4 in an organic solvent, ultrasonically cleaning it for 5 to 10 minutes, and then naturally drying it to obtain the white bamboo material.

[0012] In some preferred embodiments of the method for preparing multi-sized, patternable white bamboo materials of the present invention, in S1, the bamboo material is selected from moso bamboo, philodendron chinense, moso bamboo or natural wood.

[0013] In some preferred embodiments of the method for preparing multi-sized, patternable white bamboo materials of the present invention, in S1, the bamboo materials are cut into bamboo tubes, bamboo slices, bamboo blocks or bamboo strips of required sizes.

[0014] In some preferred embodiments of the method for preparing multi-sized, patternable white bamboo materials of the present invention, in S3, the alkaline solution is a sodium hydroxide solution, a potassium hydroxide solution, a calcium hydroxide solution or an ammonia solution with a mass concentration of 5-15%.

[0015] In some preferred embodiments of the method for preparing multi-sized, patternable white bamboo materials of the present invention, in S3, coating the bamboo material surface with bleaching liquid specifically comprises coating the bamboo material surface as a whole to prepare overall white bamboo material or coating the bamboo material surface partially to prepare patterned white bamboo material.

[0016] In some preferred embodiments of the method for preparing multi-sized and patternable white bamboo materials of the present invention, in S3, the bleaching liquid is a 2-10 mol / L hydrogen peroxide solution.

[0017] In some preferred embodiments of the method for preparing multi-sized, patternable white bamboo materials of the present invention, in S4, the light source is natural sunlight, a solar simulator or a 36W ultraviolet lamp.

[0018] In some preferred embodiments of the method for preparing multi-sized and patternable white bamboo materials of the present invention, the organic solvent in S5 is ethanol or acetone.

[0019] Another aspect of the present invention provides a multi-size, patternable white bamboo material, which is prepared by the preparation method and has a whiteness (reflectivity) of ≥90%.

[0020] Another aspect of the present invention provides a multi-size, patternable white bamboo material in the fields of artificial boards and light management.

[0021] Compared with the prior art, the method for preparing multi-sized and patternable white bamboo materials of the present invention has the following advantages:

[0022] (1) The method for preparing multi-sized, patternable white bamboo materials of the present invention has low requirements on the size of raw materials. It is not necessary to process the bamboo materials into bamboo pieces. Bamboo tubes can be directly used as raw materials, which retains the natural structural characteristics of the bamboo materials and can prepare large-sized products. This solves the problem that only small-sized white bamboo samples can be obtained by using the current solution bleaching method using cut bamboo pieces as raw materials. The preparation method has a wide range of applications and can directly prepare products of various sizes.

[0023] (2) The technical means used for bleaching bamboo in the preparation method of multi-size and patternable white bamboo described in the present invention is photocatalytic in-situ oxidation of lignin, which utilizes the strong ultraviolet absorption capacity of lignin units to enable bamboo to capture more ultraviolet light; at the same time, the multi-level pore structure of bamboo itself is utilized to ensure the efficient penetration of hydrogen peroxide solution on the bamboo skeleton, and also provide a path for ultraviolet transmission; a small amount of low-concentration alkaline solution, such as 10% sodium hydroxide solution, is introduced to enhance the oxidation capacity of hydrogen peroxide; when ultraviolet light passes through the bamboo channel, the chromophore of lignin is photocatalyzed to generate lignin free radicals, and the lignin free radicals are further oxidized by hydrogen peroxide to obtain white bamboo; this method only requires coating a layer of hydrogen peroxide solution on the surface of the bamboo tube, without placing the entire bamboo tube in the solution, which greatly reduces the consumption of compounds and directly utilizes the abundant solar energy in nature. The entire preparation process is simple, environmentally friendly, low in energy consumption, high in efficiency and low in cost;

[0024] (3) The method for preparing multi-size, patternable white bamboo materials of the present invention is more flexible, and can selectively oxidize bamboo materials to obtain white bamboo materials with different patterns on the surface; a hydrogen peroxide solution is applied to a limited area on the surface of a bamboo tube, and then irradiated under sunlight to obtain a patterned white bamboo material; this method solves the problem that solution bleaching can only bleach the entire bamboo tube and cannot perform local pattern bleaching, and provides more possibilities for the intelligent processing of new bamboo materials;

[0025] (4) The white bamboo prepared by the method for preparing multi-sized, patternable white bamboo has a high whiteness (≥90%) while maintaining the structural integrity of the bamboo. The prepared white bamboo has high mechanical strength. The method avoids the disadvantages of traditional solution bleaching, which causes the bamboo to be loose in structure, easy to crack or even directly break, and the final sample has low whiteness due to long-term immersion in chemical agents. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 In Example 1 of the present invention, white bamboo material is prepared from bamboo pieces;

[0027] Figure 2 In Example 2 of the present invention, white bamboo material is prepared from bamboo tubes;

[0028] Figure 3 The white bamboo tube bamboo material prepared in Example 2 of the present invention;

[0029] Figure 4 The patterned white bamboo material prepared in Example 3 of the present invention;

[0030] Figure 5 The mechanical properties test results of Example 1 of the present invention, Comparative Example 1, Comparative Example 2, and natural bamboo are compared. DETAILED DESCRIPTION

[0031] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0032] The present invention will be described in detail below with reference to the embodiments and the accompanying drawings.

[0033] Example 1

[0034] To prepare white bamboo chips, the steps are as follows:

[0035] 1) Selection and pretreatment of bamboo materials: Select mature bamboo materials without mold, worm holes or cracks. Use cross-cut bamboo tubes as raw materials and grind off the wax layer on the surface and the film inside the bamboo tubes.

[0036] 2) Drying of bamboo: Cut the bamboo tube obtained in step 1) into bamboo pieces with a size of 50 mm×20 mm×2 mm, and dry them at 100° C. for 48 hours;

[0037] 3) bleaching solution treatment: placing the bamboo pieces obtained in step 2) in a 10 wt % sodium hydroxide solution, soaking for 10 min at room temperature, taking them out to dry, and then coating the surface of the bamboo pieces with a layer of 2 mol / L hydrogen peroxide solution;

[0038] 4) Light treatment: placing the bamboo pieces obtained in step 3) under sunlight for photocatalytic oxidation until the bamboo pieces turn white;

[0039] 5) Cleaning: The white bamboo pieces obtained in step 4) were placed in ethanol, ultrasonically cleaned for 5 minutes, and then dried naturally to obtain Figure 1 White bamboo pieces shown.

[0040] Example 2

[0041] To prepare the white bamboo tube, the steps are as follows:

[0042] 1) Selection and pretreatment of bamboo materials: Select mature bamboo materials without mold, worm holes or cracks. Use cross-cut bamboo tubes as raw materials and grind off the wax layer on the surface and the film inside the bamboo tubes.

[0043] 2) Drying of bamboo: Cut the bamboo tube obtained in step 1) into bamboo tubes with a size of 50 mm (diameter of 30 mm, wall thickness of 5 mm), and dry them at 110° C. for 65 h;

[0044] 3) bleaching liquid treatment: placing the bamboo tube obtained in step 2) in a 10 wt % potassium hydroxide solution, soaking for 15 min at room temperature, taking it out and drying it, and then coating the surface of the bamboo tube with a layer of 5 mol / L hydrogen peroxide solution;

[0045] 4) Light treatment: placing the bamboo tube obtained in step 3) under ultraviolet light for photocatalytic oxidation until the bamboo tube turns white;

[0046] 5) Cleaning: The white bamboo tube obtained in step 4) is placed in acetone, ultrasonically cleaned for 10 minutes, and then dried naturally to obtain Figure 2 , Figure 3 White bamboo tube shown.

[0047] Example 3

[0048] To prepare patterned white bamboo, the steps are as follows:

[0049] 1) Selection and pretreatment of bamboo materials: Select mature bamboo materials without mold, worm holes or cracks. Use cross-cut bamboo tubes as raw materials and grind off the wax layer on the surface and the film inside the bamboo tubes.

[0050] 2) Drying of bamboo: Cut the bamboo tube obtained in step 1) into bamboo tubes with a size of 50 mm (diameter of 30 mm, wall thickness of 5 mm), and dry them at 110° C. for 65 h;

[0051] 3) bleaching liquid treatment: the bamboo tube obtained in step 2) is placed in a 10wt% calcium hydroxide solution, soaked at room temperature for 10 minutes, taken out and dried, and then a layer of 4mol / L hydrogen peroxide solution is selectively coated on the surface of the bamboo tube according to patterns such as "five-pointed star", "square", "turtle", "material", "HUAT", "X", etc.;

[0052] 4) Light treatment: placing the bamboo tube obtained in step 3) under sunlight for photocatalytic oxidation until the bamboo tube partially turns white;

[0053] 5) Cleaning: The white bamboo tube obtained in step 4) is placed in ethanol, ultrasonically cleaned for 10 minutes, and then dried naturally to obtain Figure 4 A patterned white bamboo tube with the motifs of "PENTAPOINTED STARS", "SQUARE", "TORTOISE", "MATERIAL", "HUAT", "X" is shown.

[0054] It can be seen from Examples 1, 2, and 3 that the method for preparing white bamboo has low requirements on the size of the raw materials. Large-sized bamboo tubes can be directly used as raw materials to produce large-sized products, and small-sized bamboo pieces can be used as raw materials to produce products of corresponding sizes. The method has a wide range of applications and is not limited by the size of the material. At the same time, the method is more flexible and can prepare both overall white bamboo and partially patterned white bamboo, and has broad application prospects.

[0055] Comparative Example 1

[0056] The bamboo is bleached by using the delignification bleaching method in the prior art.

[0057] Comparative Example 2

[0058] The bamboo is bleached by using a lignin modification bleaching method in a solution in the prior art.

[0059] The mechanical strength test of the products prepared in Example 1, Comparative Example 1 and Comparative Example 2 was carried out. The test results are as follows: Figure 4 shown.

[0060] Depend on Figure 5 It can be seen that the product prepared by lignin-modified bleaching in Comparative Example 1 and the product prepared by lignin-modified bleaching in Comparative Example 2, due to the problem of the treatment method, makes the bamboo structure very loose and very easy to crack and break, resulting in poor mechanical properties; while the product prepared by the photocatalytic bleaching process adopted in Example 1 has much better mechanical properties than Comparative Examples 1 and 2, and has a smaller attenuation amplitude than that of natural bamboo, and basically retains the good mechanical properties characteristics of natural bamboo.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing multi-sized, patternable white bamboo materials, characterized in that: The steps include: S1. Selection and pretreatment of bamboo: Select mature bamboo with good appearance, cut it into required size, and polish off the wax layer on the surface and the film inside; S2, drying of bamboo materials: drying the bamboo materials obtained in S1 at 80-110° C. for 24-72 hours; S3, bleaching liquid treatment: placing the bamboo obtained in S2 in an alkaline solution, soaking for 10 to 20 minutes at room temperature, taking it out to dry, and then applying bleaching liquid on the surface of the bamboo; S4, light treatment: placing the bamboo obtained in S3 under a light source for photocatalytic oxidation until the overall color or partial color of the bamboo turns white; S5, cleaning: placing the bamboo material obtained in S4 in an organic solvent, ultrasonically cleaning it for 5 to 10 minutes, and then naturally drying it to obtain the white bamboo material.

2. The method for preparing multi-sized, patternable white bamboo materials according to claim 1, characterized in that: In S1, the bamboo material is selected from moso bamboo, cycad bamboo, moso bamboo or natural wood.

3. The method for preparing multi-sized, patternable white bamboo materials according to claim 1, characterized in that: In S1, the bamboo material is cut into bamboo tubes, bamboo slices, bamboo blocks or bamboo strips of required sizes.

4. The method for preparing multi-sized, patternable white bamboo materials according to claim 1, characterized in that: In S3, the alkaline solution is a sodium hydroxide solution, a potassium hydroxide solution, a calcium hydroxide solution or an ammonia solution with a mass concentration of 5-15%.

5. The method for preparing multi-sized, patternable white bamboo materials according to claim 1, characterized in that: In S3, coating the bamboo surface with bleaching liquid specifically involves coating the bamboo surface as a whole to prepare an overall white bamboo material or coating the bamboo surface partially to prepare a patterned white bamboo material.

6. The method for preparing multi-sized, patternable white bamboo materials according to claim 1, characterized in that: In the S3, the bleaching liquid is a 2-10 mol / L hydrogen peroxide solution.

7. The method for preparing multi-sized, patternable white bamboo materials according to claim 1, characterized in that: In S4, the light source is natural sunlight, a solar simulator or a 36W ultraviolet lamp.

8. The method for preparing multi-sized, patternable white bamboo materials according to claim 1, characterized in that: The organic solvent in S5 is ethanol or acetone.

9. The multi-sized, patternable white bamboo material prepared by the preparation method according to any one of claims 1 to 8, characterized in that: Its whiteness is ≥90%.

10. The use of multi-sized, patternable white bamboo material according to claim 9, characterized in that: Applications in the fields of wood-based panels and light management.

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